Epithelial membrane protein 2 regulates sphingosylphosphorylcholine-induced keratin 8 phosphorylation and reorganization: Changes of PP2A expression by interaction with alpha4 and caveolin-1 in lung cancer cells

Eun Ji Lee, Mi Kyung Park, Hyun Ji Kim, Eun Ji Kim, Gyeoung Jin Kang, Hyun Jung Byun, Chang Hoon Lee

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Sphingosylphosphorylcholine (SPC) is found at increased in the malignant ascites of tumor patients and induces perinuclear reorganization of keratin 8 (K8) filaments that contribute to the viscoelasticity of metastatic cancer cells. However, the detailed mechanism of SPC-induced K8 phosphorylation and reorganization is not clear.We observed that SPC dose-dependently reduced the expression of epithelial membrane protein 2 (EMP2) in lung cancer cells. Then, we examined the role of EMP2 in SPC-induced phosphorylation and reorganization of K8 in lung cancer cells. We found that SPC concentration-dependently reduced EMP2 in A549, H1299, and other lung cancer cells. This was verified at the mRNA level by RT-PCR and real-time PCR (qPCR), and intracellular variation through confocal microscopy. EMP2 gene silencing and stable lung cancer cell lines established using EMP2 lentiviral shRNA induced K8 phosphorylation and reorganization. EMP2 overexpression reduced K8 phosphorylation and reorganization. We also observed that SPC-induced loss of EMP2 induces phosphorylation of JNK and ERK via reduced expression of protein phosphatase 2A (PP2A). Loss of EMP2 induces ubiquitination of protein phosphatase 2A (PP2A). SPC induced caveolin-1 (cav-1) expression and EEA1 endosome marker protein but not cav-2. SPC treatment enhanced the binding of cav-1 and PP2A and lowered binding of PP2A and alpha4. Gene silencing of EMP2 increased and gene silencing of cav-1 reduced migration of A549 lung cancer cells.Overall, these results suggest that SPC induces EMP2 down-regulation which reduces the PP2A via ubiquitination induced by cav-1, which sequestered alpha4, leading to the activation of ERK and JNK.

Original languageEnglish (US)
Pages (from-to)1157-1169
Number of pages13
JournalBiochimica et Biophysica Acta - Molecular Cell Research
Volume1863
Issue number6
DOIs
StatePublished - Jun 1 2016

Bibliographical note

Funding Information:
This study was supported by grants from the National Research Foundation ( 2011-0015839 , No. 2011-0022074 ), and the Research Program for New Drug Target Discovery (No. 2011-0030173 ), and the Basic Science Research Program , through the NRF ( NRF-2014R1A2A1A01004016 ).

Keywords

  • Alpha 4
  • Epithelial membrane protein 2
  • Keratin 8 phosphorylation
  • Keratin 8 reorganization
  • Protein phosphatase 2A
  • Sphingosylphosphorylcholine

Fingerprint Dive into the research topics of 'Epithelial membrane protein 2 regulates sphingosylphosphorylcholine-induced keratin 8 phosphorylation and reorganization: Changes of PP2A expression by interaction with alpha4 and caveolin-1 in lung cancer cells'. Together they form a unique fingerprint.

Cite this